Magnetic head

ABSTRACT

A magnetic head comprises: an induction type head for recording including a lower magnetic core, a writing gap film formed on the lower magnetic core, an upper magnetic core having a track portion and a portion spreading from the track portion, a plurality of insulating films laminated between the lower magnetic core and the upper magnetic core, and a coil formed between the plurality of insulating films. One of the plurality insulating films is an insulating film determining a zero throat level position. The track portion of the upper magnetic core is an air bearing surface. A magnetoresistance effect typehead for reproducing includes a lower shielding film and a magnetoresistance effect sensor film is formed between the lower shielding film and the lower magnetic core. The position where the upper magnetic core spreads is located nearer to the air bearing surface than the tip end position arranged nearest to the air bearing surface among the tip end positions of the insulating films formed on the insulating film determining the zero throat level position. This can provide a magnetic head having good magnetic characteristics and improved accuracy in the width of a track on the air bearing surface.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a magnetic head of the typehaving a recording head and a reproducing head separately and used for amagnetic recording/reproducing device and a magnetic disc device usingthe magnetic head.

[0003] 2. Description of the Related Art

[0004] One of the magnetic heads of the type having a recording head anda reproducing head separately is a magnetic head using amagnetoresistance effect element (hereinafter referred to as “MRelement”). The MR element uses the characteristics that resistancechanges in response to a change in the intensity of magnetic field andits reproducing output does not depend on the running speed of amagnetic recording medium, but depends only on the amount of magneticflux of a magnetic signal. Therefore, the MR element can produce asufficient reproducing output even if the running speed is low and hencehas an advantage in increasing the recording density of a magneticrecording device and in reducing the size thereof.

[0005] The magnetic head of this kind is disclosed in IEEE Transactionon Magnetics, Vol. 26, page 1689, 1990, for example.

[0006] The magnetic head has increased the number of turns of coil inorder to write by an intense magnetic field and to produce a largereproducing output and an insulating film for insulating the coil hasbeen formed in multiple layers. Japanese Unexamined Patent PublicationNo. Hei 3-156714 discloses a technology for covering the whole multipleinsulating films by the other insulating film in order to eliminate alevel difference produced by the multiple insulating films.

[0007] On the other hand, in order to improve the areal recordingdensity of magnetic recording, it will be necessary in the future toextensively increase a track density as well as a linear recordingdensity. This requires that the track of a magnetoresistance effect head(hereinafter referred to as “MR head”) be formed in still narrower widthand with higher accuracy.

[0008] The conventional magnetic head described above is not sufficientin the accuracy of a zero throat level position because it has the otherinsulating film covering the whole multiple insulating films forinsulating the coil. In this connection, a throat level portion means aportion from the air bearing surface of a magnetic core to the tip endof interlayer insulating films for vertically separating an uppermagnetic core from a lower magnetic core more than the thickness of awrite gap. A zero throat level position means the tip end position ofthe insulating film nearest to the air bearing surface of the magneticcore among the interlayer insulating films.

[0009] On the other hand, the structure having no other insulating filmcovering the whole insulating films for insulating the coil has thefollowing problem. The upper magnetic core is formed by a methodcomprising the steps of forming an underlying layer for plating on theinsulating film for insulating the coil, forming a frame thereon by aphotoresist, and electroplating the space thereof with a conductivefilm. However, when a frame pattern is formed, the light from a patternexposure system is reflected by the underlying layer for plating at thelevel difference portion of the insulating film to produce halation. Thephotoresist of the unnecessary portion is exposed to the light.Therefore, for example, there exists a problem that a part of themagnetic core forming a track is not formed in a desired shape and thatthe accuracy of a track width is not sufficient.

[0010] Next, the conventional magnetic head will be described withreference to drawings. FIG. 1A is a plan view of an upper magnetic coreand FIG. 1B is a cross sectional view showing a part of the magnetichead. In FIG. 1B, a first layer insulating film 7 is formed on a writegap film 20 and a second layer insulating film 9 a for protecting a coil8 is formed thereon and a third layer insulating film 9 b for protectingthe coil 8 is formed thereon and further an upper magnetic core 10 isformed thereon via an underlying layer 25 for plating.

[0011] The upper magnetic core 10 is formed by the use of a patternformed from a positive photoresist (not shown) on the underlying layer25 for plating formed on the third layer insulating film 9 b formed onthe second layer insulating film 9 a formed on the first layerinsulating film 7.

[0012] As shown in FIG. 1A, if the position Pa where the upper magneticcore 10 spreads is located on the level difference portion of the secondlayer insulating film 9 a or to the right hand side in the drawing, thatis, in the direction away from the air bearing surface 36, a depressionis produced in the side of the resist pattern of the track portion 10 a(in FIG. 1A, a left portion from the position Pa where the uppermagnetic core spreads) by the reflecting light from the underlying film25 for plating to produce a spreading portion 10 b at the track portion10 a of the upper magnetic core 10, when the photoresist is exposed tothe light.

[0013] In the structure like this, since the portion where the magneticflux of the upper track is to be contracted is expanded, the magneticcharacteristics deteriorate. Further, when the air bearing surface isformed, if the track portion corresponding to the air bearing surface isexpanded, there are produced variations in the width of the track of theair bearing surface 36.

SUMMARY OF THE INVENTION

[0014] It is an object of the present invention to provide a magnetichead having good magnetic characteristics and improved accuracy in thewidth of a track on an air bearing surface.

[0015] It is another object of the present invention to provide amagnetic disc device using the magnetic head like this.

[0016] In order to achieve the object, the magnetic head in accordancewith the present invention comprises a magnetoresistance effect typehead for reproducing and an induction type head for recording and hastwo or more interlayer insulating films vertically separating an uppermagnetic core from a lower magnetic core more than the thickness of awrite gap. The position where the upper magnetic core spreads from atrack portion is located nearer to an air bearing surface than the tipend position nearest to the air bearing surface among the tip endpositions of the insulating films which are formed on the insulatingfilm determining the zero throat level position and have leveldifferences to each other.

[0017] If the insulating film which is formed on the insulating filmdetermining the zero throat level position and has a level difference isone layer, it is essential only that the position where the uppermagnetic core spreads from the track portion is located in front of (tothe air bearing surface side of) the tip end position, that is, the tipposition of the level difference, of the insulating film. If two or moreinsulating films with a level difference to each other are arranged, itis required only that the position where the upper magnetic core spreadsfrom the track portion should be located in front of the tip endposition of the insulating film whose tip end position is nearest to theair bearing surface.

[0018] The position where the upper magnetic core spreads may be locatedon the insulating film determining the zero throat level or nearer tothe air bearing surface side, that is, directly on the write gap film.However, it is desirable that it is located about 0.5 μm or more behindthe air bearing surface, that is, to the zero throat level side.

[0019] Further, in order to achieve the second object of the presentinvention, the magnetic disc device in accordance with the presentinvention comprises a rotatable magnetic recording medium having aninformation recording layer, a drive motor for rotating the magneticrecording medium at high speeds, a control means for controlling therotation of the drive motor, a magnetic head provided with anelectromagnetic converter for writing or reading information into orfrom the recording layer and movable on the recording layer of themagnetic recording medium. The magnetic head is used as this magnetichead, a circuit means for controlling the information by which themagnetic head write or read the information, a positioning means forpositioning the magnetic head at a predetermined position on themagnetic recording medium at high speeds, and a control circuit forcontrolling the positioning means.

[0020] In order to achieve the object of the present invention, themagnetic head in accordance with the present invention comprises: aninduction type head for recording including a lower magnetic core, awrite gap film formed on the lower magnetic core, an upper magnetic corehaving a track portion and a portion spreading from the track portion, aplurality of insulating films laminated between the lower magnetic coreand the upper magnetic core, and a coil formed between the plurality ofinsulating films. One of the plurality of insulating films is aninsulating film determining a zero throat level position. The trackportion of the upper magnetic core is an air bearing surface.

[0021] The magnetic head further comprises a magnetoresistance effecttype head for reproducing including a lower shielding film and amagnetoresistance effect sensor film formed between the lower shieldingfilm and the lower magnetic core. The position where the upper magneticcore spreads is located nearer to the air bearing surface than the tipend position arranged nearest to the air bearing surface among the tipend positions of the insulating films formed on the insulating filmdetermining the zero throat level position.

[0022] In the magnetic head, in the case where the plurality ofinsulating films comprise a first insulating film and a secondinsulating film and the first insulating film is the insulating filmdetermining the zero throat level position. When the second insulatingfilm is formed on the first insulating film, the position where theupper magnetic core spreads is located between the tip end of the secondinsulating film and the air bearing surface.

[0023] Further, in the magnetic head, in the case where the plurality ofinsulating films comprise a first insulating film, a second insulatingfilm and a third insulating film and the first insulating film is theinsulating film determining the zero throat level position and thesecond insulating film is formed on the first insulating film and thethird layer insulating film is formed on the second layer insulatingfilm and the tip end position of the second insulating film is locatednearer to the air bearing surface than the tip end position of the thirdinsulating film, the position where the upper magnetic core spreads islocated between the tip end of the second insulating film and the airbearing surface.

[0024] Still further, in the magnetic head, in the case where theplurality of insulating films comprise a first insulating film, a secondinsulating film and a third insulating film and the second insulatingfilm formed on the first insulating film is the insulating filmdetermining the zero throat level position and the third insulating filmis formed on the second insulating film, the position where the uppermagnetic core spreads is located between the tip end of the thirdinsulating film and the air bearing surface.

[0025] Furthermore, in the magnetic head, in the case where theplurality of insulating films comprise a first insulating film and asecond insulating film. The second insulating film formed on the firstinsulating film is the insulating film determining the zero throat levelposition, the position where the upper magnetic core spreads is locatednearer to the air bearing surface side than the zero throat levelposition.

[0026] In order to achieve the object of the present invention, amagnetic disc device in accordance with the present invention comprises:a rotatable magnetic recording medium having an information recordinglayer; a drive motor for rotating the magnetic recording medium at highspeeds; and a magnetic head movable on the recording layer of themagnetic recording medium in order to write or read the information intoor from the recording layer. The magnetic head comprises: an inductiontype head for recording including a lower magnetic core, a write gapfilm formed on the lower magnetic core, an upper magnetic core having atrack portion and a portion spreading from the track portion, aplurality of insulating films laminated between the lower magnetic coreand the upper magnetic core, and a coil formed between the plurality ofinsulating films. One of the plurality of insulating films being aninsulating film determining the zero throat level position and the tipend of the track portion of the upper magnetic core being the airbearing surface. The magnetic device further comprises amagnetoresistance effect head for reproducing including a lowershielding film and a magnetoresistance effect sensor film formed betweenthe lower shielding film and the lower magnetic core. The position wherethe upper magnetic core spreads is located nearer to the air bearingsurface than the tip end position arranged nearest to the air bearingsurface among the tip end positions of the insulating films formed onthe insulating film determining the zero throat level position.

[0027] In the magnetic disc device, in the case where the plurality ofinsulating films comprise a first insulating film and a secondinsulating film and the first insulating film is the insulating filmdetermining the zero throat level position and the second insulatingfilm is formed on the first insulating film, the position where theupper magnetic core spreads is located between the tip end of the secondinsulating film and the air bearing surface.

[0028] Further, in the magnetic disc device, in the case where theplurality of insulating films comprise a first insulating film, a secondinsulating film and a third insulating film and the first insulatingfilm is the insulating film determining the zero throat level positionand the second insulating film is formed on the first insulating filmand the third insulating film is formed on the second insulating filmand the tip end position of the second insulating film is located nearerto the air bearing surface than the tip end position of the thirdinsulating film, the position where the upper magnetic core spreads islocated between the tip end of the second insulating film and the airbearing surface.

[0029] Still further, in the magnetic disc device, in the case where theplurality of insulating films comprise a first insulating film, a secondinsulating film and a third insulating film and the second insulatingfilm formed on the first insulating film is the insulating filmdetermining the zero throat level position and the third insulating filmis formed on the second insulating film, the position where the uppermagnetic core spreads is located between the tip end of the thirdinsulating film and the air bearing surface.

[0030] Furthermore, in the magnetic disc device, in the case where theplurality of insulating films comprise a first insulating film and asecond insulating film and the second insulating film formed on thefirst insulating film is the insulating film determining the zero throatlevel position, the position where the upper magnetic core spreads islocated nearer to the air bearing surface side than the zero throatlevel position.

[0031] In order to achieve the object of the present invention, amagnetic disc device in accordance with the present invention comprises:a rotatable magnetic recording medium having an information recordinglayer; a drive motor for rotating the magnetic recording medium at highspeeds; a control means for controlling the rotation of the drive motor;a magnetic head provided with an electromagnetic converter for writingor reading the information into or from the recording layer and movableon the recording layer of the magnetic recording medium; a circuit meansfor controlling the information by which the magnetic head writes orreads the information into or from the magnetic recording medium; apositioning means for positioning the magnetic head at a predeterminedposition on the magnetic recording medium at high speeds; and a controlcircuit for controlling the positioning means. The magnetic head furthercomprises a magnetoresistance effect type head for reproducing and aninduction type head for recording, wherein the tip end of the trackportion of the upper magnetic core of the induction type magnetic headconstitutes the air bearing surface and interlayer insulating filmsvertically separating the upper magnetic core from a lower magnetic coremore than the thickness of a write gap include two or more insulatingfilms and have a coil therebetween. The position where the uppermagnetic core spreads from the track portion is located nearer to theair bearing surface side than the tip end position nearest to the airbearing position among the tip end positions of the insulating filmsformed on the insulating film determining the zero throat level andhaving a level difference to each other.

[0032] Further, in the magnetic disc device, the insulating film havinga level difference is one layer and the position nearest to the airbearing surface among the tip end positions of the insulating films isthe tip end position of the insulating film having the level difference.

[0033] These and other objects, features and advantages of the presentinvention will be apparent from the following more particulardescription of the preferred embodiments of the present invention, asillustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034]FIG. 1A is a plan view of an upper magnetic core and FIG. 1B is across sectional view showing a part of a magnetic head.

[0035]FIG. 2A is a plan view showing one preferred embodiment of themagnetic head in accordance with the present invention and FIG. 2B is across sectional view thereof.

[0036]FIG. 3 is a partial cross sectional view in perspective of themagnetic head shown in FIG. 2.

[0037]FIG. 4 is a schematic perspective view showing one preferredembodiment of the magnetic disc provided with the magnetic head inaccordance with the present invention.

[0038]FIG. 5A is a plan view showing another preferred embodiment of themagnetic head in accordance with the present invention and FIG. 5B is across sectional view thereof.

[0039]FIG. 6A is a plan view showing still another preferred embodimentof the magnetic head in accordance with the present invention and FIG.6B is a cross sectional view thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] Magnetic discs in accordance with the present invention and onepreferred embodiment of the magnetic disc device using the magnetic discwill hereinafter be described with reference to the accompanyingdrawings.

[0041]FIG. 2A is a plan view showing one preferred embodiment of themagnetic head in accordance with the present invention and FIG. 2B is across sectional view thereof. In the drawings, like reference numeralsdesignate like or corresponding components in FIG. 1 and the descriptionthereof will be omitted except for differences in constitution.

[0042] As shown in the plan view of the magnetic head shown in FIG. 2A,the magnetic head in accordance with the present invention is providedwith an upper magnetic core 10 and insulating films. As is evident fromFIG. 2B, the insulating films comprises a first layer insulating film 7,a second layer insulating film 9 a, and a third layer insulating film 9b.

[0043] As is evident from FIG. 2B, the magnetic head comprises a lowershielding film 2, an MR lower gap film 32 made of alumina and formed onthe lower shielding film 2, a magnetoresistance effect sensor film 3formed on the MR lower gap film 32, an MR upper gap film 34 formed onthe magnetoresistance effect sensor film 3 and the MR lower gap film 32,an upper shielding film-cum-lower magnetic core film 6 formed on the MRupper gap film 34, and a write gap film 20 formed on the upper shieldingfilm-cum-lower magnetic core film 6 formed on the MR upper gap film 34.In the present preferred embodiment, a zero throat level position P0 islocated at the tip end of the first layer insulating film 7.

[0044] In the present preferred embodiment, a position Pa where theupper magnetic core 10 shown in FIG. 2A spreads is located on theinsulating film determining the zero throat level position P0. In thiscase, on the first layer insulating film 7, and nearer to an air bearingsurface 36 than the tip end 37 of the second layer insulating film 9 aformed thereon. Therefore, when the photoresist described above isexposed to light, the periphery of a track portion 10 a is not exposedto the light reflected by an underlying layer 25 for plating and hencethe track portion 10 a can be formed like a nearly linear structure.

[0045] In the magnetic head of the present preferred embodiment, aninduction-type head for recording comprises the upper shielding film-cum- lower magnetic core 6, the write gap film 20, the coil 8, the firstlayer insulating film 7, the second layer insulating film 9 a, the thirdlayer insulating film 9 b, the underling layer 25 for plating, and theupper magnetic core. A magnetoresistance effect type head comprises thelower shielding film 2, the MR lower gap film 32, the MR upper gap film34, the magnetoresistance effect sensor film 3, the upper shieldingfilm- cum- lower magnetic core film 6.

[0046] Next, a process for manufacturing the magnetic head will bedescribed with reference to FIG. 3.

[0047]FIG. 3 is a partial cross sectional view in perspective of themagnetic head shown in FIG. 2. In the drawing, the lower shielding film2 formed of a magnetic film made of Permalloy (NiFe) or the like and thelower gap film 32 formed of insulating film made of alumina or the like(not shown in FIG. 3 to avoid making the drawing complex, see FIG. 2B)are formed on a ceramic substrate 1 and the magnetoresistance effectsensor film 3 is formed like stripes. The magnetoresistance effectsensor film 3 comprises a plurality of films such as magnetoresistanceeffect films using magnetic material such as Permalloy (NiFe) and biasfilms for biasing the magnetoresistance effect films. Further, at theside of them are formed a magnetic domain control film 4 for stabilizingthe magnetic domain of the magnetoresistance effect sensor film 3 and anelectrode conductive film 5 for supplying a current for making themagnetoresistance effect sensor film 3 function as a sensor. Theelectrode conductive film 5 is formed by a lift-off method. The uppergap film 34 (not shown, see FIG. 2B) formed of the insulating film madeof alumina or the like are formed on the electrode conductive film 5. Inorder to put the electrode conductive film 5 into contact with a leaderline 12, the desired portion of the upper gap film 34 on the electrodeconductive film 5 is removed to make an aperture. The leader line 12 ofthe electrode conductive film 5 extends outside from the lower shieldingfilm 2. Further, the leader line 12 is simultaneously formed of the samefilm as the upper shielding film- cum- lower magnetic core film 6 and ispatterned in a predetermined shape. This film is formed of the magneticfilm such as Permalloy or the like. Further, the write gap film 20 (notshown, see FIG. 2B) is formed thereon.

[0048] Next, as shown in FIG. 2B, the first layer insulating film 7 madeof resist is formed on the write gap film 20. The coil 8 for passing acurrent through the induction-type head is formed on the first layerinsulating film 7 by a plating method and the second layer insulatingfilm 9 a is formed thereon by the same process as used for the firstlayer insulating film 7. Further, the coil 8 and the third layerinsulating film 9 b are formed thereon. In this manner, a multiple-layerstructure is formed as shown in FIG. 2B. Although this multiple-layerstructure is not shown in FIG. 3, it can be understood with reference toFIG. 2B. Then, the upper magnetic core 10 is formed thereon.

[0049] The upper magnetic core 10 is formed by the use of a platingfilm. First, a resist frame for a magnetic plating film is formed on theunderlying layer 25 for plating. At this time, by suitably shaping masksfor forming the insulating films 7, 9 a, 9 b and the resist frame forthe magnetic plating film, as shown in FIG. 2A, 2B, the position Pawhere the upper magnetic core 10 spreads is located nearer to the airbearing surface 36 than the tip end of the second layer insulating film9 a on the first layer insulating film 7 determining the zero throatlevel.

[0050] In this respect, since the above-mentioned upper shielding film-cum- lower magnetic core film 6 is larger in area than the insulatingfilms 7, 9 a, 9 b, the first layer insulating film 7, the second layerinsulating film 9 a and the third layer insulating film 9 b can beformed in a nearly flat plane, whereby defects caused by a break in acoil can be reduced in number.

[0051] Finally, a terminal 11 for connecting a lead wire and aprotective film for protecting an element are formed. This is the end ofthe process for manufacturing the magnetic head. In this connection, thesame elements are arranged at equal intervals on a wafer and aremanufactured at the same time and then are divided into individualmagnetic heads. Ten wafers were manufactured in accordance with themanufacturing process shown by the preferred embodiment described aboveand the size of upper track of the wafer was measured from the airbearing surface for all the elements. The variation 3 σ in measurementswas 0.13 to 0.19 μm.

[0052] In order to compare with the magnetic head of the presentpreferred embodiment, a magnetic head having a conventional structure inwhich the position where the upper magnetic core spreads is located atthe position shown in FIG. 1A and FIG. 1B was manufactured in accordancewith the manufacturing method described with reference to FIG. 3. Thesize of the upper track was measured from the air bearing surface forall the elements and the variation 3 σ in measurements was 0.35 to 0.45μm. In the case of this conventional structure, the variation in thesize of track was large and hence this conventional structure cannotrealize a head for high recording density.

[0053] Next, one preferred embodiment of a magnetic disc device usingthe magnetic head in accordance with the present invention will bedescribed.

[0054]FIG. 4 is a schematic perspective view showing one preferredembodiment of a magnetic disc device provided with the magnetic head inaccordance with the present invention. As shown in FIG. 4, the magneticdisc device comprises a plurality of magnetic discs 13 stacked at equalintervals on a spindle 38, a magnetic head 15 held by a rotary carriageassembly 14, a voice coil motor 16 for driving the carriage assembly 14,and a base 17 for supporting these members. Further, the magnetic discdevice is provided with a voice coil motor control circuit forcontrolling the voice coil motor 16 and a control means for controllinga drive motor rotating the magnetic discs 13 (both of them are not shownin FIG. 4) according to a signal from a higher level system such as amagnetic disc control system and is connected to the higher level systemvia an interface unit for exchanging signals with the higher levelsystem and a read/write circuit for controlling a current passed throughthe magnetic head. In this respect, the employment of the thin-filmmagnetic head of the preferred embodiment described above as themagnetic head 15 can improve the reliability of the magnetic disc deviceand the assembly yield thereof.

[0055] Next, another preferred embodiment will be described withreference to FIG. 5A and FIG. 5B.

[0056]FIG. 5A is a plan view of a main part showing another preferredembodiment of the magnetic head in accordance with the presentinvention, and FIG. 5B is a cross sectional view of the main part. Sincethe part of the magnetic head not shown in FIG. 5 is the same as themagnetic head shown in FIG. 2A and FIG. 2B, the part is omitted. Themagnetic head shown in FIG. 5 is different from the magnetic head shownin FIG. 2 in the insulating film determining the zero throat levelposition and the position Pa where the upper magnetic core 10 spreads.

[0057] Another preferred embodiment of the magnetic head in accordancewith the present invention will hereinafter be described with referenceto FIG. 5. In this magnetic head, the zero throat level position P0 isdetermined by the second layer insulating film 9 a. Therefore, comparedwith the magnetic head of the type determining the zero throat levelposition P0 by the first layer insulating film 7 shown in FIG. 2, themagnetic head of this type can increase the thickness of the insulatingfilm near the zero throat level, that is, the thickness of the secondlayer insulating film 9 a extending in the direction of the air bearingsurface 36 from the tip end of the first layer insulating film 7 and canreduce the possibility of deterioration of magnetic characteristics suchas magnetic flux leak or the like and further can improve the insulatingperformance of the writing element.

[0058] Although the insulating film determining the zero throat level isthe first layer insulating film 7 in the preferred embodiment in FIG. 2,the second layer insulating film 9 a determines the zero throat level inanother preferred embodiment in FIG. 5. As shown in FIG. 5A, theposition Pa where the upper magnetic core 10 spreads is located on thesecond layer insulating film 9 a and near to the air bearing surface 36than the tip end of insulating film formed on the second layerinsulating film 9 a and having a level difference thereto, that is, thetip end of the third layer insulating film 9 b.

[0059] Next, still another preferred embodiment in accordance with thepresent invention will be described with reference to FIG. 6.

[0060]FIG. 6A is a plan view of a main part showing the still anotherpreferred embodiment of the magnetic head in accordance with the presentinvention, and FIG. 6B is a cross sectional view of the main part. Sincethe part of the magnetic head not shown in FIG. 6 is the same as themagnetic head shown in FIG. 2A and FIG. 2B, the part is omitted. Themagnetic head shown in FIG. 6 is different from the magnetic head shownin FIG. 2 in the insulating film determining the zero throat levelposition P0 and in the position Pa where the upper magnetic core 10spreads.

[0061] As shown in FIG. 6, in this magnetic head, the position Pa wherethe upper magnetic core 10 spreads is located near to the air bearingsurface 36 than the tip end of insulating film determining the zerothroat level, that is, the tip end of the second layer insulating film 9a. Therefore, the position Pa where the upper magnetic core 10 spreadsis located between the air bearing surface 36 and the zero throat levelposition P0 and the volume of the upper magnetic core 10 increases fromthis position. This increases magnetic characteristics, in particular,overwriting characteristics.

[0062] The magnetic heads of still another preferred embodiment shown inFIG. 6 and the magnetic heads of FIG. 5 having the structure in whichthe position Pa where the upper magnetic core 10 spreads is located inthe back (in the right hand side in the drawing) of the tip end of theinsulating film determining the zero throat level, that is, on thesecond layer insulating film 9 a were manufactured. Then the magneticcharacteristics were measured for the magnetic heads. The test resultsshowed that the magnetic heads of still another preferred embodimentshown in FIG. 6 improved the overwriting characteristics by 30 to 40% onaverage.

[0063] In the present invention, the zero throat level position P0designates the tip end of the insulating film extending nearest to theair bearing surface 36 of the upper magnetic core 10 among the pluralityof insulating films. That is, the zero throat level position P0designates the tip end of the first layer insulating film 7 in thepreferred embodiment in FIG. 2B, and the tip end of the second layerinsulating film 9 a in the preferred embodiment in FIG. 5B and FIG. 6B.

[0064] As described above, according to the present invention, themagnetic characteristics and the accuracy of the width of the track ofthe air bearing surface can be improved by determining the positionwhere the upper magnetic core of the magnetic head spreads.

[0065] Further, since the magnetic head according to the presentinvention has high accuracy in the width of the track, it can realizethe magnetic disc device with high recording density.

[0066] The present invention may be embodied in other specific formswithout departing from the spirit or essential characteristics thereof.The present embodiment is therefore to be considered in all respects asillustrative and not as restrictive, the scope of the present inventionbeing indicated by the appended claims rather than by the foregoingdescription and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

What is claimed is:
 1. A magnetic head comprising: an induction typehead for recording including a lower magnetic core, a write gap filmformed on the lower magnetic core, an upper magnetic core having a trackportion and a portion spreading from the track portion, a plurality ofinsulating films laminated between the lower magnetic core and the uppermagnetic core, and a coil formed between the plurality of insulatingfilms, one of the plurality of insulating films determining a zerothroat level position and the track portion of the upper magnetic corebeing an air bearing surface; and a magnetoresistance effect type headfor reproducing including a lower shielding film and a magnetoresistanceeffect sensor film formed between the lower shielding film and the lowermagnetic core, wherein the position where the upper magnetic corespreads is located nearer to the air bearing surface than the tip endposition arranged nearest to the air bearing surface among the tip endpositions of the insulating films formed on the insulating filmdetermining the zero throat level position.
 2. A magnetic head accordingto claim 1, wherein in a case where the plurality of insulating filmscomprise a first insulating film and a second insulating film and thefirst insulating film determines the zero throat level position and thesecond insulating film is formed on the first insulating film, aposition where the upper magnetic core spreads is located between thetip end of the second insulating film and the air bearing surface.
 3. Amagnetic head according to claim 1, wherein in a case where theplurality of insulating films comprise a first insulating film, a secondinsulating film and a third insulating film and the first insulatingfilm determines the zero throat level position and the second insulatingfilm is formed on the first insulating film and the third layerinsulating film is formed on the second layer insulating film and thetip end position of the second insulating film is located nearer to theair bearing surface than the tip end position of the third insulatingfilm, a position where the upper magnetic core spreads is locatedbetween the tip end of the second insulating film and the air bearingsurface.
 4. A magnetic head according to claim 1, wherein in a casewhere the plurality of insulating films comprise a first insulatingfilm, a second insulating film and a third insulating film and thesecond insulating film formed on the first insulating film determinesthe zero throat level position and the third insulating film is formedon the second insulating film, a position where the upper magnetic corespreads is located between the tip end of the third insulating film andthe air bearing surface.
 5. A magnetic head according to claim 1,wherein in a case where the plurality of insulating films comprise afirst insulating film and a second insulating film and the secondinsulating film formed on the first insulating film determines the zerothroat level position, a position where the upper magnetic core spreadsis located nearer to the air bearing surface side than the zero throatlevel position.
 6. A magnetic head comprising a magnetoresistance effecttype head for reproducing and an induction type magnetic head forrecording, wherein the tip end of the track portion of the uppermagnetic core of the induction type magnetic head constitutes an airbearing surface and interlayer insulating films vertically separatingthe upper magnetic core from the lower magnetic core more than athickness of a write gap include two or more insulating films and theinsulating films have a coil therebetween, and wherein a position wherethe upper magnetic core spreads from the track portion is located nearerto the air bearing surface than the tip end position nearest to the airbearing surface among the tip end positions of the insulating filmsarranged on the insulating film determining the zero throat level andhaving a level difference to each other.
 7. A magnetic head according toclaim 6, wherein the insulating film having a level difference is onelayer and the position nearest to the air bearing surface among the tipend positions of the insulating films is the tip end position of theinsulating film having a level difference.
 8. A magnetic disc devicecomprising: a rotatable magnetic recording medium having an informationrecording layer; a drive motor for rotating the magnetic recordingmedium at high speeds; and a magnetic head movable on the recordinglayer of the magnetic recording medium in order to write or read theinformation into or from the recording layer; wherein the magnetic headcomprises: an induction type head for recording including a lowermagnetic core, a write gap film formed on the lower magnetic core, anupper magnetic core having a track portion and a portion spreading fromthe track portion, a plurality of insulating films laminated between thelower magnetic core and the upper magnetic core, and a coil formedbetween the plurality of insulating films, one of the plurality ofinsulating films determining the zero throat level position and the tipend of the track portion of the upper magnetic core being the airbearing surface; and a magnetoresistance effect head for reproducingincluding a lower shielding film and a magnetoresistance effect sensorfilm formed between the lower shielding film and the lower magneticcore, and wherein a position where the upper magnetic core spreads islocated nearer to the air bearing surface than the tip end positionarranged nearest to the air bearing surface among the tip end positionsof the insulating films formed on the insulating film determining thezero throat level position.
 9. A magnetic disc device according to claim8, wherein in a case where the plurality of insulating films comprise afirst insulating film and a second insulating film and the firstinsulating film determines the zero throat level position and the secondinsulating film is formed on the first insulating film, a position wherethe upper magnetic core spreads is located between the tip end of thesecond insulating film and the air bearing surface.
 10. A magnetic discdevice according to claim 8, wherein in a case where the plurality ofinsulating films comprise a first insulating film, a second insulatingfilm and a third insulating film and the first insulating filmdetermines the zero throat level position and the second insulating filmis formed on the first insulating film and the third insulating film isformed on the second insulating film and the tip end position of thesecond insulating film is located nearer to the air bearing surface thanthe tip end position of the third insulating film, a position where theupper magnetic core spreads is located between the tip end of the secondinsulating film and the air bearing surface.
 11. A magnetic disc deviceaccording to claim 8, wherein in a case where the plurality ofinsulating films comprise a first insulating film, a second insulatingfilm and a third insulating film and the second insulating film formedon the first insulating film determines the zero throat level positionand the third insulating film is formed on the second insulating film, aposition where the upper magnetic core spreads is located between thetip end of the third insulating film and the air bearing surface.
 12. Amagnetic disc device according to claim 8, wherein in a case where theplurality of insulating films comprise a first insulating film and asecond insulating film and the second insulating film formed on thefirst insulating film determines the zero throat level position, aposition where the upper magnetic core spreads is located nearer to theair bearing surface side than the zero throat level position.
 13. Amagnetic disc device comprising: a rotatable magnetic recording mediumhaving an information recording layer; a drive motor for rotating themagnetic recording medium at high speeds; a control means forcontrolling the rotation of the drive motor; a magnetic head providedwith an electromagnetic converter for writing or reading the informationinto or from the recording layer and movable on the recording layer ofthe magnetic recording medium; a circuit means for controlling theinformation by which the magnetic head writes or reads the informationinto or from the magnetic recording medium; a positioning means forpositioning the magnetic head at a predetermined position on themagnetic recording medium at high speeds; and a control circuit forcontrolling the positioning means, wherein the magnetic head comprisinga magnetoresistance effect type head for reproducing and an inductiontype head for recording and the tip end of the track portion of theupper magnetic core of the induction type magnetic head constitutes theair bearing surface, and interlayer insulating films verticallyseparating the upper magnetic core from a lower magnetic core more thana thickness of a write gap include two or more insulating films and havea coil therebetween, and wherein a position where the upper magneticcore spreads from the track portion is located nearer to the air bearingsurface side than the tip end position nearest to the air bearingposition among the tip end positions of the insulating films formed onthe insulating film determining the zero throat level and having a leveldifference to each other.
 14. A magnetic disc device according to claim13, wherein the insulating film having a level difference is one layerand the position nearest to the air bearing surface among the tip endpositions of the insulating films is the tip end position of theinsulating film having the level difference.